note-parser

Parse note names (in scientific notation) with javascript. Given a string, obtain a hash with note properties (including midi number and frequency)

If you need parse interval names take a look to interval-notation

Usage

Install via npm: npm i --save note-parser and require it:

var parser = require('note-parser')
parser.parse('c#4') // => { letter: 'C', acc: '#', ... midi: 61, freq: 277.1826309768721 }

The returned object will contain:

letter: the uppercase letter of the note
acc: the accidentals of the note (only sharps or flats)
pc: the pitch class (letter + acc)
step: s a numeric representation of the letter. It's an integer from 0 to 6 where 0 = C, 1 = D ... 6 = B
alt: a numeric representation of the accidentals. 0 means no alteration, positive numbers are for sharps and negative for flats
chroma: a numeric representation of the pitch class. It's like midi for pitch classes. 0 = C, 1 = C#, 2 = D ... It can have negative values: -1 = Cb.

If the note name has octave, the returned object will additionally have:

If the parameter isTonic is set to true another property is included:

tonicOf: the rest of the string that follows note name (left and right trimmed)

If you are interested only in midi numbers or frequencies, you can use midi function:

parser.midi('A4') // => 69
parser.midi('blah') // => null
parser.midi(60) // => 60
parser.midi('60') // => 60

or the freq function:

parser.freq('A4') // => 440
parser.freq('A3', 444) // => 222
parser.freq(69) // => 440

With the build function you can convert back to string:

parser.build(parser.parse('cb2')) // => 'Cb2'

Alternatively the build function accepts step, alteration, octave parameters:

parser.build(3, -2, 4) // => 'Fbb4'

To run the test clone this repo and:

npm install
npm test

MIT License